Le Duc Cuong, Do Huy Toan, Dao Dinh Cham, Nguyen Ba Thuy, Nguyen Ba Thuy, Du Van Toan, Nguyen Minh Huan, Nguyen Quoc Trinh, Tran Anh Tu, Le Xuan Sinh

Main Article Content

Abstract

In the present study, an open-source coupled numerical model based on Delft3D source code was performed and applied to simulate the hydrodynamic changes due to the Super Typhoon Rammasun in the Gulf of Tonkin (GTK). The results indicated that the typhoon strongly affects the current, water level, wave fields, and suspended sediment transport in the western coastal areas of the GTK. The simulated wave height field reflects the wavefield caused by the Super Typhoon Rammasun, and the maximum wave height was 6.8m during the Typhoon Rammasun event. The current is affected by the strong wind caused due to the typhoon in the surface layer. Accordingly, current velocity and significant wave height increased distinctly by 4 and 9 times, respectively, more than the normal condition. In the western coastal areas, the maximum sea level falls to about 0.7m, and the current velocity was 0.25-0.3m/s (during ebb tide stages) greater than it was in normal conditions during Super Typhoon Rammasun event. The moving Super Typhoon Rammasun resulted in suspended sediment concentration (SSC) increasing by 2 times more than normal monsoon conditions and also strengthened suspended sediment transport in the GTK, which was mostly controlled by strong waves during typhoon events. Simulated results showed that SSC in the GTK varied dramatically in temporal and spatial distribution, with the maximum value in wet seasons because of large sediment discharge around the river mouth.


 

Keywords: Gulf of Tonkin, Delf3D, Rammasun Typhoon, Hydrodynamics, Suspended Sediment

References

[1] K. Kleinen, Historical Perspectives on Typhoons and Tropical Storms in the Natural and Socio-Economic System of Nam Dinh (Vietnam), Journal of Asian Earth Sciences. Vol. 29, 2007, pp. 523-531, https://doi.org/ 10.1016/j.jseaes. 2006.05.012.
[2] N. B. Thuy, The Risk of Typhoon and Storm Surge Along the Coast of Vietnam, Vietnam Journal of Marine Science and Technology, Vol. 19, 2019, pp. 327-336, https://doi.org/10.15625/1859-3097/19/3/13899.
[3] L. C. van Rijn, Mathematical Modeling of Morphological Processes in the Case of Suspended Sediment Transport, Thesis, Delft Tech. Univ., Delft, The Netherlands, 1987.
[4] D. B. Duy, N. D. Thanh, T. Q. Duc, P. V. Tan, Seasonal Predictions of the Number of Tropical Cyclones in the Vietnam East Sea Using Statistical Models. VNU Jounal of Science: Earth and Environmental Sciences, Vol. 35, 2019, pp. 45-57, https://doi.org/10.25073/2588-1094/vnuees.4379.
[5] P. T. Ha, H. D. Huy, P. Q. Nam, J. Katzfey, J. McGregor, N. K. Chi, T. Q. Duc, N. M. Linh, P. V. Tan, Implementation of Tropical Cyclone Detection Scheme to CCAM Model for Seasonal Tropical Cyclone Prediction over the Vietnam East Sea, VNU Jounal of Science: Earth and Environmental Sciences,Vol. 35, 2019, pp. 49-60, https://doi.org/10.25073/2588-1094/vnuees.4384.
[6] P. Wessel, W. H. F. Smith, A Global, Self-Consistent, Hierarchical, High-Resolution Shoreline Database,
J. Geophys. Res, Vol. 101, 1996, pp. 8741-8743, https://doi.org/10.1029/96JB00104.
[7] P. Weatherall, K. M. Marks, M. Jakobsson, T. Schmitt, S. Tani, J. E. Arndt, M. Rovere, D. Chayes, V. Ferrini, R. Wigley, A New Digital Bathymetric Model of the World's Oceans, Earth and Space Science, Vol. 2, 2015, pp. 331-345, https://doi.org/10.1002/2015EA000107.
[8] J. J. Becker, D. T. Sandwell, W. H. F. Smith, J. Braud, B. Binder, J. Depner, D. Fabre, J. Factor, S. Ingalls, S-H. Kim, R. Ladner, K. Marks, S. Nelson, A. Pharaoh, R. Trimmer, J. Von Rosenberg, G. Wallace, P. Weatherall, Global Bathymetry and Elevation Data at 30 Arc Seconds Resolution: SRTM30_PLUS. Marine Geodesy, An International Journal of Ocean Survey, Mapping, and Sensing, Vol. 32, 2009, pp. 355-371, hppts://doi.org/10.1080/01490410903297766.
[9] W. H. F. Smith, D. T. Sandwell, Bathymetric Prediction from Dense Satellite Altimetry and Sparse Shipboard Bathymetry, J. Geophys. Res, Vol. 99, 1994, pp. 21803-21824, hppts://doi.org/10.1029/94JB00988.
[10] W. H. F. Smith, D. T. Sandwell, Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings, Science, Vol. 277, 1997, pp. 1956-1962, hppts://doi.org/10.1126/science.277.5334.1956.
[11] G. D. Egbert, Y. E. Svetlana, Efficient Inverse Modeling of Barotropic Ocean Tides, Journal of Atmospheric and Oceanic Technology. Vol. 19, 2002, pp. 183-204, https://doi.org/ 10.1175/1520-0426(2002)019<0183:EIMOBO> 2.0.CO;2
[12] JMA, Annual Report on the Activities of the RSMC Tokyo – Typhoon Center, Japan Meteorological Agency, Tokyo, 2014, Appendix 1, http://www.jma.go.jp/jma/jma-eng/jma center/rsmc-hp-pub-eg/AnnualReport/2014/Text/Text2014.pdf (accessed on: January 1st, 2019).
[13] WL | Delft Hydraulics, 2010. Delft3D-FLOW User Manual Version 3.04.12566. WL | Delft Hydraulics, Delft, The Netherlands, 2010.
[14] R. C. Ris, N. Booij, L. Holthuijsen, A Third-Generation Wave Model for Coastal Regions, Part I, Model Description and Validation. Vol. 104, 1999, pp. 7649-7656, https://doi.org/10.1029/98JC02622.
[15] L. Holthuijsen, N. Booij, T. Herbers, A Prediction Model for Stationary, Short-Crested Waves in Shallow Water with Ambient Currents, Coastal Engineering, Vol. 13, 1989, pp. 23-54, https://doi.org/10.1016/0378-3839(89)90031-8.
[16] J. S. Galappatti, Introduction to a Depth-Integrated Model for Suspended Transport, TUD Technical University Delft, Report, pp. 6-86, 1983.
[17] R. Galappatti, A Depth-Integrated Model for Suspended Transport, Fac. of Civ. Eng., Delft Univ. of Technol., Delft, Netherlands, 1983.
[18] R. L. Soulsby, Dynamics of Marine Sands. Thomas Telford Publishing, London, England, 1997, pp. 87-95.
[19] T. Chai, R. R. Draxler, Root Mean Square Error (RMSE) or Mean Absolute Error (MAE) – Arguments Against Avoiding RMSE in the Literature, Geoscientific Model Development, Vol. 7, 2014, pp. 1247-1250, https://doi.org/10.5194/gmd-7-1247-2014.